Interpol

Interpol is a Glyphs plugin for real-time variable font interpolation preview. It allows you to visualize and interact with interpolated glyph shapes, detect interpolation kinks, and fix them using automated tools.

Features

Installation

  1. Download the Interpol.glyphsPlugin package
  2. Double-click to install, or manually copy to:
    • ~/Library/Application Support/Glyphs 3/Plugins/
  3. Restart Glyphs

Getting Started

Enabling the Preview

  1. Open a variable font with at least 2 masters
  2. Go to View → Show Interpol to enable the reporter
  3. The palette panel will appear showing axis sliders and a few other controls

Interpol Overview

The Palette Panel

The palette appears when Interpol is enabled and shows:

Interpol Palette

Axis Sliders

Axis Assignment (for Mouse Tool)

Two dropdown menus let you assign axes to mouse movements:

The Mouse Tool

The Interpol tool allows you to control axis values by dragging the mouse.

Interpol Tool

  1. Select the Interpol tool from the toolbar (keyboard shortcut: A by default)
  2. Click and drag in the canvas:
    • Horizontal drag controls the first assigned axis
    • Vertical drag controls the second assigned axis
  3. The interpolated preview updates in real-time as you drag

Note: When the tool is active, normal selection and editing are disabled. Switch back to the Select tool (V) to edit.

Display Options Menu

Right-click on the Edit View to access display options:

Interpol Contextual Menu

Preview Options

Master Tracking

Layer Dimming

Preview Window & Bubble

Space Preview

Kink Detection

Visualizing Kinks

When Show Kinks is enabled, Interpol marks problematic nodes:

Interpol Kink Preview

Kink indicators only appear when the interpolation severity exceeds a threshold, so minor kinks are ignored.

The Dekink Panel

The Dekink panel provides automated tools to fix interpolation kinks by synchronizing point ratios across masters.

Interpol Dekink Panel

Opening the Panel

  1. Select one or more smooth on-curve points with kinks
  2. Access the panel via right-click and select Dekink Window…

The panel is non-modal - you can keep it open while working in Glyphs.

Panel Controls

Preview Dekink (checkbox)

Interpol Dekink Preview

Mode Selection

Manual Control Mode:
Gives you full control over how the dekinking process works.

Auto (Preserve Shape) Mode:
Automatically finds the best balance between dekinking and preserving the original curve shapes. This mode:

Selection Counter

Shows how many smooth points are selected and how many have kinks:

Note: The panel automatically filters your selection to only operate on points that actually have kinks.

Apply Dekink Button

Applies the dekinking to all masters. This operation:

Dekink Workflow

  1. Enable kink visualization: Turn on Show Kinks in the display menu
  2. Select problematic nodes: Click nodes marked with pink indicators
  3. Open Dekink panel: Right-click on the edit view and select Dekink Window…
  4. Choose mode:
    • Try Auto mode first for automatic optimization
    • Use Manual mode if you need specific control
  5. Preview: Enable “Preview Dekink” to see changes in green
  6. Adjust (Manual mode only):
    • Move the Change slider to balance on-curve vs off-curve movement
    • Toggle Compensate Curves if shape preservation is important
  7. Apply: Click “Apply Dekink” to commit changes
  8. Verify: Check that kink indicators disappear or become smaller

Settings

Access settings via Window → Interpol Settings...

Available Settings

Tool Keyboard Shortcut

Preview Fill Color

Preview Outline/Nodes/Handles Color

Kink Indicator Color

Dekink Window Preview Color

Line Style

Resetting to Defaults

Click ”Reset to Defaults” to restore all original settings.


Version: 3.0
Author: José Solé @ Dogray Type Foundry
License: [Your License]